(1) Technical Field:
This invention pertains to valves useful to control and vary flow between inside and outside the valve. The invention particularly pertains to a sliding sleeve type valve useful in a well conduit and a compatible selective pressure operated shifting tool which operates to open, close and vary the area open for flow through the sleeve valve wall.
(2) Background Information:
Previous sliding sleeve valves did not provide structure for varying area open for flow through wall flow openings in the valve by moving the valve sleeve to intermediate positions between open and closed positions. Previous selective pressure operated shifting tools compatible with sliding sleeve valves do not operate the sleeve valve to intermediate positions between open and closed position, decreasing the area of openings open for flow when operated from open toward closed position and increasing area of openings open for flow when operated from closed toward open position.